It is clinical commonplace that normal cephalic growth produces racial, familial and individually specific patterns of size and shape. Similarly many craniofacial malformations are characterized by syndrome specific head growth patterns. In all cases, normal and abnormal, such patterned growth can occur only by processes of adjustive cranial skeletal growth. While it is agreed that such processes must exist, no comprehensive conceptualization exists as to what these processes are or how they are regulated. Using models both normal and experimentally produced abnormal cephalogenesis in the rat, all of which involve marked alterations in growth patterns, we propose to describe and analyze all stages of normal adjustive cranial growth, to demonstrate the processes involved and to validate these results by a similar study of the sequential compensatory changes occurring in experimentally produced cephalic deformations. This will permit creation of a general theory of adjustive cranial growth.